Insufficient sleep puts young drivers at greater risk of a car crash, a large study by Australian researchers has found.

The new findings, published in the journal JAMA Paediatrics, show that sleeping less on weekends and sleeping six hours or less per night over a sustained period are both factors that increase the chance of run-off road crashes.

The authors of the study analysed the association between sleep and motor vehicle crashes in newly licensed people aged between 17 and 24. Measuring a sample size of 20,000, the participants were followed up on average two years after being enrolled in the study.

Beginning in 2003, the researchers analysed police-reported crash data and driver sub-groups to determine who had an increased crash risk.

The study found that less sleep per night significantly increased young drivers’ crash risk and that less sleep on weekends increases run-off road and late night crash risks.

“Young drivers who sleep six hours a night or less have an increased risk of crashing their vehicle and that’s an effect that’s isolated from other risks for crash, since we were able to take those into consideration,” said an author of the study, Associate Professor Alexandra Martiniuk, Senior Research Fellow at The George Institute for Global Health.

“Existing literature tended to look at more drastic sleep reduction, so usually looking at five hours sleep a night or less, whereas we looked at six hours sleep a night or less, which is obviously much more common.”

Young people who slept less on the weekend are likely to crash at night between 8pm and 6am and were more likely to have run-off-road crashes, Dr Martiniuk said.

“We’re quickly learning that young people are getting less and less sleep because of school, work or socialising such as being on Facebook at night or texting their friends.”

Sleep needs

Leon Lack, Professor of Psychology at Flinders University and a sleep expert, said that other studies have shown that younger people tend to be higher risk takers in general.

“Even though, intellectually, they may appreciate they will be sleepy and should not be driving, in reality they may do so anyway,” said Professor Lack.

“We have recently done a nationwide study on sleepiness. As a group, people of this age tend to report more sleepiness. Sleepiness continues to be reported up to about the age of 50 and then tends to decline with older age groups,” he said.

“Sleep need of that younger age group is still quite high, an average of about eight hours a night with individual variations. Younger people are perhaps pushing the boundaries a little more than older people.”

Professor Lack said young people may feel they don’t have enough time for sleep.

“They may have a second job, they may be studying full time, they may be married and if they have young kids, they have a lot of commitments,” he said.

“That, in conjunction with potentially a bit of alcohol and the effect of circadian rhythms on late night driving, can have a very strong effect to produce extreme sleepiness.”